Node

aka Node.js or nodejs

Text copyleft teknopaul CC Attribution-NonCommercial
Node.js logo & design copyright joyent

What is it?

Server-side JavaScript

Command-line JavaScript

No browser

Chrome v8 VM + node/lib (not window)
i.e. not a lot, posix, net, http, crypto, buffer, process

You can read the whole API in 1 hour

I recommend you do read it

Chrome v8 is an open source google sponsored JavaScript runtimehttp://code.google.com/p/v8/API herehttp://nodejs.org/docs/v0.5.0/api/all.html

Where do I get it?

https://github.com/joyent/node.git

You pay nothing

99% of the work is done by google/v8 in the name of chrome

the rest paid for by joyent and "the community"

You need to install git the version control system by Linux himself, its a ballache you get used to it.

joyent is the company that sponsors node development.

Lets play

mkdir playground

cd playground

git clone https://github.com/joyent/node.git

cd node

./configure && make
sudo make install

vi hellow-world.js OR download eclipse

If you Have certificate errors try

env GIT_SSL_NO_VERIFY=true git clone https://github.com/joyent/node.git

you need open ssl and c++ build tools

Copy the hello world from the node home page

http://nodejs.org/

Quick start

Should be up and running quite quickly

IMHO one of nodes strong points

Quick boot

Hello World is a web-server

Could quite easily do printf hello world too

Npm == yum for node, slick!

Get nodeunit too

Npm installs with

curl http://npmjs.org/install.sh | sh

If you are lucky

Then man npmn

Or

Npnm install nodeunit

What is Node for?

Event Driven

I assume you know this bit

Stop me if you need an introduction to NIO

Lots of too technical stuff on t'internet basically even drivven means

evtsrc.on('someEvent' , function(data) { // this happens when the event is fired});

All IO in node is event driven

ie. not String data = readFile();

More like

fs.readFile(name, 'utf-8', function(data) {});

What node does best?

Nothing

Until something happens

Node is good at doing nothing no swapping threads around in the background, when it is idle it really is idle.

When something happens ALL the code is executed until the end of the function or functions responding to the event.

What to write

Web Projects network stuff to run on NIX servers, although Ryan is working on Windoze

not specifically WWW , in fact very much not just web, TCP sockets stuff, (not so much UDP)

N.B. Buffer is painful compared to unsigned byte unsigned long long and all C's network friendly types

C and C++ node can chuck about Buffers nicely and also node native is very fast (need to test that)

Note to self (have a session on byte and bit processing with node)

Look into web sockets, if you are using web sockets you should be using node as the server probably.

Node can handle many concurrent connections as long as they are not doing much.

What to write

Web ProjectsXMPP / Chat

Disqus

Stock tickers

Anything web scale that runs fast

What to write

Desktop@see nodetoy

each instance is one thread and as much memory as a tab

Nothing out there yet, this is my idea

Mini servers, perhaps lots of them

What to write

Scriptingyeah man #!/usr/local/bin/node works

As long as you can handle async scripts you now have a very nice scripting API

e.g little network clients

It is better writing JS than bloody Perl or PHP!

N.B. Sync IO exists

What to write

UtilsIf its missing write it, please

Npm has no registration required

Some simple stuff is missing

Ryan is aiming to write a platform we need to write the tooling

Anything goes

What not to write

OK I'm bad at this

npm ls

npm search blah

http://search.npmjs.org/

Apache (doh! I tried that)

N.B. Node is single threaded so if you do somewthing that takes a very long time in the thread you hang the system completely, for example if you process some very large JPEG image that takes a few seconds to do, nothing else happens.

To do that sort of thing push a job onto a rabbitMQ queue for processing on a separate thread and put an event listener on the reply.

Tips for setting up a project?

Code style

Don't be scared of "globals" 2 global scopes
no namespace hacks if (typeof ns == 'undefined') ns = {};

A file is a module, it is difficult to pollute modules with other code
you can fuck up require or search paths, but just don't

In the browser it IS complicated, people just ignore the complexity.

Read google's guides.

In node just write pleasant looking code.

This is such a relief, and makes big projects conceivable

http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml
http://portawiki.abnoctus.com/view/Object_Oriented_Event_Handlers.html

Reiterate a file IS a module.

import the module with

var xxx = require(../../somejsfile.js);

Only exported functions are visible

e.g. you must call

module.exports.addUp = function(a, b) { return a + b;}

Wot no maven

Node has cool modules system, better that JavaScript or goog.require() or CommonJS BUT all about files and dirs, no packaging

Pwd sensitive, you will get bitten by this!

Npm or npm -g

../../../node_modules

/var/data/local/project/latest/node/myproject
bad idea

Adduser node_modules :o)

If you

require('someModule')

Node looks for

./node_modules/someModule.js./node_modules/someModule/index.js

And a bunch of other places

Including ../../../node_modules

Right back to /node_modules/

A bit simple, but it works.

Project layout

Node and npm in the system path/home/me/node_workspace/....../node_modules/sax
/dom
/my_funky_mod /my_proj1
/my_proj2

This is just my tips there is no obligatory project structure like there is in maven.

Module files

./README.md./package.json./index.js./lib/ ./test/./example/./deps/ (or NOT)

N.B. There is no ./target or ./classes or ./out needed

README.md is a markdown text file for github, not needed if you don't host at github

package.json is an npm thing RTFM it is pretty simple

./lib is a recommended standard, not a requirement

./example/ is polite

./deps/ is probably a bad idea use npm

Application files

./src/js ./src/client ./src/server./src/conf./bin/ (still run from source)./test/js ./test/data./foo ./bar./../node_modulesThe aim is that the following should be painlessvar foo = require('foo');

Have a think about where your client side and server side files reside, because you might want to share code between the two.

Sharing code needs some hacking like

if(module.exports) { Module.exports.funktion= funktion;}else { var ns = new Object(); ns.funktion = funktion;}

nodeunit

Nodeunit forces pwd to be the directory the script is in.

Half you code relies on relative directories , then nodeunit blows the theory.

Dont have relative paths for resources e.g. ../conf/config.xml is becoming a problem

Again. Just a tip, relative paths for resources turns out nasty, I plan to fix this in nodeunit for eclipse, I have submitted a pull request.

Whats cool

jsdom server side dom "rendering" (we should have a session on this) weld + server side jQuery :o)

WebSockets these are built in to http core in node for an obvious reason.

haml + sass early options , there are many more templates now but this is cool

template engines that run client side and server side

JSDoc

nodeunit

Cloud9, but clearly my eclipse plugins is cooler :o)

request

Redis, nosql, couchdb, mongodb and the like

bpedro's map/reduce DB

Node is cool and has a community that is into the hip stuff going on at the mo, kind of railsy type people.

Read up on these things they are funky but also functional. (treble pun there, gedit? ed.)

Whats not cool

JavaScript is fluffy;

Windows support

No APIs, no standards, just user contributed code

1 Thread, no standard clustering

No locks is good & bad, no real concurrency

1GB RAM limit

Like everything JavaScript, its a hack

Joyent is the sponsor, it may not be in google's long term interest

Node has some serious limits, so you can do everything in node, it is not C++ or Java. It is good at what it is good at and bad at everything else.

Node is a serious option

Support - its hip, get on irc

Modules - not just gadgets anymore

TDD nodeunit

Structure JSDoc

SOA/RPC/i18n/crypto

Performance not the best, but not bad

50% less validation code, opportunities for re-use

Node is a serious option

Good hosting options

Cloud9, VMWare Azure coming

https://no.de/

https://github.com/joyent/node/wiki/hosting

Can I write everything on Node

1 thread is tricky for noobs, callbacks are tricky to debug

Good for model 3, I know its not cool, but you need templating in the real world for division of labour

Depends on your legacy, libs integrate well, but most services will not integrate with node, existing code uses threads, managing JMS is somehow difficult

That 50% validation code saving is very tempting!

(talking mostly about webapps)

Model3 is a me term, Model 1 is servlet returning HTMLModel 2 is a servlet processing then forwarding to a JSPModel 3 is a HTML page talking JSON to the server RPC style with no Java2HTML at all.